drop a piano on his head (thing)

What a director would say back in the early 20th century during the making of a silent comedy picture. If the movie just wasn't funny up until this point, this was the pat answer. "Drop a piano on his head. That's funny!" This answer was also used on occasion in cartoons throughout the 1930s through 1990s. Sometimes it wasn't a piano; Sometimes it was something else, but the sentiment was the same.